Optical and electrochemical properties of poly(o-toluidine) multiwalled carbon nanotubes composite Langmuir-Schaefer films.

Conducting poly(o-toluidine) (POT) with multiwalled carbon nanotubes (MWNTs) nanocomposite (POT-MWNTs) was synthesized by oxidative polymerization. Chloroform solutions of the material were used for the optical characterizations by means of UV-visible spectroscopy and for the fabrication of Langmuir-Schaefer (LS) films. LS films were fabricated at the air-liquid interface by using 0.1 M HCl aqueous solution as the subphase to study the electrochemical properties of the nanocomposite by means of cyclic voltammetry and photoelectrochemical techniques. The optical characterizations gave proof that the presence of MWNTs inside the polymeric matrix produced no change in the (pi-pi*) transition of POT structure, indicating that the polymeric chains were simply wrapped around and not doped by MWNTs. The electrochemical investigations highlighted significant changes in the redox properties of POT-MWNTs LS films with respect to pure POT. The cyclic voltammetric study also revealed high electrochemical stability, confirmed by the estimation of the diffusion coefficient and the photoelectrochemical response of the nanocomposite LS films. This characteristic turned out to be more evident than that obtained in our earlier studied poly(o-anisidine)-MWNTs (POAS-MWNTs) system.